Apparatus for mixing air and liquified petroleum gases



March 13, 1956 Filed Feb. 19, 1955 F. E. DRAKE APPARATUS FOR MIXING AIRAND LIQUIFIED PETROLEUM GASES '2 44 I 12 &4 41

2 Sheets-Sheet l 29 46 25 ii 31 6 v2 24 11 11 1/ 3 I L1 7 R l 13 FL "I[1 INVENTOR.

AT TOR NEYS F. E. DRAKE 2,738,261

APPARATUS FOR MIXING AIR AND LIQUIFIED PETROLEUM GASES March 13, 1956 2Sheets-Sheet 2 Filed Feb. 19, 1953 INVENTOR. 'XW M BY ATT RNEYS FORMIXING AIR AND, LIQUIFIED PETROLEUM GASES Drake, Pelham, N. Y., assignorof one-half to Harry W. Townsend, New Rochelle, N. Y.

Application February 19, 1953, Serial No. 337,763

7 Claims. c1. 48-180) APJP ARATUS This invention relates to apparatusfor mixing air with vaporized petroleum products, such aspropane andbutane. In order to control the heating value of gas made from propane,butane, or other volatile hydrocarbons, or mixtures of hydrocarbons, itis-the usual practice to mix a definite quantity of air with the vaporor gas before supplying it to the distribution lines.

It is an object of this invention to provide improved apparatus formixing air with the gas from vaporized hydrocarbons; and it is aparticular object to obtain a highly accurate control of the heatingvalue of'the gas without the use of expensive and highly complicatedcontrol mechanism.

One of the simpler ways by which air can be supplied to use a pluralityof aspirators, connected in parallel,

and the number of aspirators in use at any one time depends upon the gasdemand. t v

It is another object of the invention to provide a gas mixer withaplurality of mixing devices connected in' 1 parallel with one anotherand operated by simple control rn e'chanism for determining which andhow many of the mixers are to operate at any one time. Moreespecially,itis-an object of the invention to control the operation of the mixersby gas pressure and without the use of electn'city'. The mixers of theprior art which haveused electricity, are rendered inoperative orrequiremanual operation in the event of a storm or other occasion whichshutsofi the electricity, sometimes for substantial periods of time. l

Other objects, features and advantages of the invention will appear orbe pointed out as the description proceeds.

In the drawing, forming a part hereof, in whichlike reference charactersindicate correspondingparts in all theyiews,

Figure 1 is :a perspective view showing the outside housing of a mixerembodying this invention;

Figure Zis a plan view of the unit shown in Figures 1, 3 and 4, with thetop of the housing removed;

Figure 3 is a rear elevation of the mixer unit of this invention withthe. back of the housing removed;

Figure 4 is aside elevation of the unit shown in Figure 3, with the sideof the housing removed;

Figure 5 is an enlarged, fragmentary and diagrammatieview of one of thegasflow control valves and its operating mechanism; Figure 6 is anenlarged, sectional view of one ofthe mixers, placed in a horizontalposition.

"Figure 1 shows the mixer unit of this invention with a housing 10supported onbed members 11. A gas'inlet connection 12 is located nearthe top and front or the and 21.

ice

2 housing 10; and a gas outletconnection 13 is located at the bottom andbackof thehousing.

The gas outlet connection 13 is fora substantially larger size of pipebecause'the gas flowing from the mixing unit has a substantial quantityof air mixed in-it and this makes the volume substantially larger.

tems having distribution pressures in excess of about 4 or 5 pounds (p.s. i. g.), compressed is supplied to the conduit 18. I

Figures 2, 3 and 4 showthe construction inside of the housinglt). Thereis an incoming gas header 20 communicating with the gas inlet connection12 and there is an outgoing gas header 21 leading to the gas outletconnection 13. A system of piping 24 leads. from theupper gas header 20to the lower and-outgoing gas header 21. A, similar system of piping 25also connects headers. 20

In each of the systems of piping 24 and 25, there is a shutoff valve 27,operated by automatic control means whichfwill be described, forcommanding the flow of gas from the header .20 to the header 21. I

The flow ofgas to each automatic shutofi valve 27 can be shut ofimanually by avalve 29 in series with the shutoff valve 27.. A by-pass.line 31 leads from .the in-,

coming gas header 20 to aconnection with thesystem of piping 24 beyondthe shutoff valve. 27.- .1 A similar bypass line 32 leads from theheader 20 to a location of the system of piping'25 beyond the shutoifvalve 27 of that system of piping. I

Referring to Figures-3 and 4, the systems of piping 24 and 25 bothextend downwardly for a substantial distance 'in the housing 10, andeach systemhas a mixer unitor aspirator 34 below the by-pass lines 31and 32. I Another shutoff valve 35 is located between the automaticshutofi valve 27 and the by-pass 31. or 32. This makes it possible toclose the piping on .both sides of the valve 27 so that this automaticvalve can be removed from the line and replaced without relieving thepressure: in the line or in any way impairing the operation of themixer. a

At each mixer unit 34 thereis an air inlet line 36, leading from theconnecting conduitr 18 through which air flows from theair :filter 17.-.Each-.o f these air inletlines 36 containsa check valve 37 forpreventing possible escapeof gas from the system in the event that flow.through the aspirator is blocked and. gas attempts to .back. up throughthe air inlet line 36. There is also a manuallyoperated air valve 38 inthe air inlet line 36.

Both of these air inlet lines 36 connect with the connecting conduit 18leading from the air filter 17. This construction makes the inventionmore compact, but it can be made with separate air'cleaners on thedifferent airinletlines. a a r In -'the construction illustrated, the:connecting conduit 18, the air filter 17, and theupstr'ea'm ends of theair inlet lines 36, aresupported from the bottom of the housing byan'upstanding support 39. f v t t Each of the shutoff valves 27 hasapressure-actuated operator 40 which will be described in detail inconnection with Fig. 5. For the present, it is sufiicient totounderstand that when pressure is applied under the operator 40, thevalve 27 isopened. r.

The gas for actuating the operators-40 is controlled from pilot controlassemblies 41 and; 42. The pilot control assembly 41 connects with' theoperator for the valve 27 in the system of piping 24, andithepilot-control assembly 42 connects'with the operator 40 for the valve 27in-the system of piping 25. Y

'The pilot control assemblies41and 42 both-receive Patented -Mar-. 13,.1956.

7 Thereis a check valve 15 on the gasoutlet connection 13.. The. airwhich is to be mixed with the gas within the housing 10 is drawn throughan air filter 17 and connect-- ing conduit 18 to the mixerswithin thehousing. For sys-:

gas from the incoming gas header 20 through tubing 43 and a pressureregulator "44, connected in" series with the tubing 43. Each of thepilot control assemblies 41 and 42 is connected with the outgoing gasheader 21 by tubing 45. Each pilot control assembly is connected withthe operator 40, which it controls, by tubing 46. (Bornpressed air canbe supplied to'the pressure regulator 44, instead of gas, at plantswhere compressed air is available. The use of gas as the working fluidtor th'evalve operators 40 has "the advantage of making the apparatus aself-contained unit.

Fig. shows the construction of the pilot control assembly 41 anditsassociated pressure-actuated operator. The construction of the otherpilot control assembly is similar. The tubing 43 leads from theregulator 44 to a control device 47.

Inthe control device 47, the gas flows into a chamber 49 in which'thereis a valve element 50. There are openings at both ends of the chamber49. The gas fromthe tubing 43 enters the chamber 4 9 through the openingat the left-hand end of the chamber, and the opening at the right-handend of the chamber leads to the ambient atmosphere. If desired, theleft-hand end of the chamber 49 can be connected bytubing to thedistribution header 21. This conserves gas and also prevents the gasfrom escaping in a confined room when the unit is indoors.

When the valve element 50 is at the left-hand end of the chamber 4.9 asshown infull lines in Fig. 5, it closes the opening which communicateswith the tubing 43-and shuts off the flow of gas into the chamber 49.

When thevalve element '50 is at the right-hand end of the chamber 49, asshown in dotted lines in Fig. 5, it prevents the escape of gas from thechamber 49 to the ambient atmosphere.

The valve element 50 has a-valve stem connected with a metal flapper 51which isheld, by amagnet 52, in position to locate the valve elements 50at the left hand end of the chamber 49. The magnet 52 is secured to oneend of an adjusting screw 53. This screw threads through a flange54-extending upwardly from the control device 47. By turning thescrew'53, the magnet can be advanced or retracted with respect to theflapper 51.

Themetal flapper 51- extends upwardly between-an adjustable abutment 58and a fixed pivot 59. The abutment 58 can be shifted'toward and from theflapper 51 by an adjusting-screw 60. The .upper end of the flapper 51 isconnected to anend fitting '61 of a .bellows 62 carried-by a fixedsupport 63.

' The bellows 62 is connected with the tubing 45, and through thistubing-communicates with the'distribution header. When the-pressurewithinthe-distribution header decreases, the -bellows 62 contracts andpulls the upper end of the-metal-flapper 51 toward the-left in Fig.SJ'This tends to rock'the' flapper 51 counter-clockwise, but because ofthe attractionof-the magnet 52 for the :flapper, the initial contractingmotion-of the bellows- 62 merely bends the metal flapper 51.

As additional energyis stored in the metal flapper .51 by bending, theenergy-eventually becomes sufficient to pull the flapper away from themagnet 52 so that the flapperpulls-the.valveelement'50. to the righthand end of thechamber 51. .With the-valve element 50 in this position,gas flows-from the tubing43, through the chamber 49, and from thechamber.49 through tubing 6.4 to a control pressure chamber-.65 of adiaphragm-operated valve 66.

'-'The.-valve'66 contains anvalve element 67 having a valve stem whichis-lpushed downwardly by .diaphragms 68 when the pressurein thechambenGSincreases sufficiently to overcomethe pressure of a spring 69which is compressed between the :lowerndiaphragm 68; and a partitionedwallet-the casingof the valve 66. DownwardmovementotlIthe-yalve element67;, shifts it, into open positionand permits-gas from the regulator. 44to flow past the valve element 67 tothe tubing 46, and throughthistubingdo thexalvercpcrator 40.

When the gas pressure in the distribution header rises,

the bellows 62 extends and pushes the upper end of the metal flapper 51toward the right hand in Fig. 5. This rocks the flapper 51 about theabutment 58 and shifts the lower end of the flapper toward the magnet52. The flapper 51 moves the valve element 50 from the dotted line tothe full line positions shown in Fig. 5 so that the flow of gas from thetubing 43 is shut off, so that the gas in the chamber 49, and in thecontrol pressure chamber 65, is free to escape past the valve stem andinto the ambient atmosphere through the opening in which the stem of thevalve element 50 slides.

This escape of gas reduces the pressure in the valve chamber 65-rapidly, and the spring 69 pushes the diaphragms 68 upwardly so that thevalve element 67 is moved into closed position by a spring 69 locatedunder the valve element.

The upper end of the stern of the valve element 67 is pointed so as toserve as a needle valve. This pointed end of the valve stem closes aport through thecenter of the lower diaphragm 68 when the diaphragms aredepressed, but after the valve element 67 closes, the furtherupwardmovement of the diaphragms 68, under pressure from'the spring 69,lifts the lower diaphragmabove the pointed end of the valve stem andpermitsuthei gas under the lower diaphragm 68 to escape vinto the spacebetween the diaphragms. From this space the gas passes through .tubingconnecting with the distribution header 21, as indicated in Fig. 5. Thisbleed outlet provides for the escape ofgas from the pressure chamber ofthevalve operator 40 so that the valve operator can return to its normalpositionunder influence of spring-operated means which will be,described.

The tubing 46 communicates with a diaphragm ,chamber 70 on the undersideof a diaphragm 71. Therc'is-a diaphragm plate 72 on top of the diaphragm71. ,This diaphragm plate 72 and the diaphragm 71, are. urged downwardlyby a spring 73.

A push-rod 74 is threaded into a boss on top. of ,the diaphragm plate 72and this push-rod 74 slides in-a bearing 75 held in the frame 76 of theoperator 40.

The'valye. 27 includes a valve element 77. This. valve element 77 ismoved into open position by a valve lifter 78 that has a stem 79 whichslides through a stuffing 00x80 and bearings 81. The lower end of t hevalve lifter stem 79 is connected with the upper end of;,the push-rod 74and operates as a unit with the push-rod. An indicator;82 ;on thepush-rod 74 moves, alonga scale 83 to indicate the. extent of opening ofthe valve element 77.

Figure 6 shows the construction of the mixer unit-or aspirator-34. Anozzle 85 discharges a stream..of,;gas from the incoming header 20 intoa throat 86 andthis stream of gas; from the nozzle 85 draws air into thethroat 86 from an air chamber 88 surrounding the nozzle,85.

The air chamber 88 is kept filled withair by the flow of new air throughthe air inlet line 36 and through the check. valve 37. I It is a featureof the invention that the check valve 37 includes a very light valveelement 90, and it is another feature of the invention thatthe air inletline 36-is of short length. These featurescombine to keep the airpressure in the chamber 88 nearly'constant, becauseany slight drop inpressure in the air chamber- 88 is sufficient to draw new air into thechamber through the short air inlet line 36. The light weight of;thecheck valve element 90 results in there being very little pressure dropnecessary to hold this valve element open.

.Both of. ,the mixers or aspirators 34 of the apparatus are similar inconstruction but they may befartd preferably are,;of diflerent size. Forexample, .th e mixer unit. 34 in the system of piping 24 may bedesigned' for a flow. of 50 0,,cubic feet of gas per hour, and,then1ixer in the system of piping 25 may be designed for a larger rate offlow. I

going gas header 21 by the tubing 45.

The two mixer units shown in the drawing are merely representative of aplurality of mixer units connected in parallel between the incoming gasheader 20 and the outgoing gas header 21.

When the apparatus is installed, the pilot control assemblies areadjusted so that they do not operate at exactly the same pressure. Thebellows 62 (Figure 5) of each pilot control assembly, is connected withthe out- In order to make the pilot control assemblies operate insequence, the adjustable abutment 58 or the magnet 52 of one pilotcontrol assembly is adjusted so that it does not operate until thebellows pressure drops to a somewhat lower value than is required tooperate the other pilot control assembly. When the mixer units are ofdiiferent capacity, the pilot control assemblies are adjusted so thatthe mixer unit of smaller capacity operates first when a demand for gasreduces the pressure in the outgoing gas header.

When the gas demand becomes so great that the first mixer cannot supplyit by working continuously, then there will be a somewhat further dropin the pressure in the outgoing gas header and the second pilot controldc vice will operate to cause gas to be supplied through the secondmixer.

When the second mixer is of considerably larger capacity than the first,and the apparatus is in a plant with I an attendant, the lower-capacitymixer may be cut out of operation by closing the valve 29. This has theefiect of making the larger mixer remain open for longer periods.Frequently repeated opening and closing of the gas line through eitherof the mixers is undesirable because there is a'tendency for the mixerto supply a flush of overly rich gas to the line when the mixer firstbegins to operate, and to supply a flush of lean gas to the line as themixer stops operating.

The preferred embodiment of the invention has been illustrated anddescribed, but changes and modifications can be made without departingfrom the invention as defined in the claims.

I claim as my invention:

1. Air-gas mixing apparatus including in combination a gas supply headerfor high pressure gas, a distributing header for an air-gas mixture atlower pressure, connecting means through which gas flows from the supplyheader to the distributing-header, said connecting means including apressure regulator and a mixer, an aspirator in the mixer operated byflow of gas through the mixer toward the distributing header, an airinlet communicating with the aspirator and through which air is drawn bythe aspirator, a valve for controlling the flow of the gas through theaspirator, actuating mechanism for the valve operated by gas pressure,gas passage connections between one of the headers and the actuatingmechanism for the valve, said actuating mechanism including a chambercommunicating with said gas passage connections to the header, a movableelement forming a wall of the chamber and movable.

in response to pressure changes in the chamber, and motion transmittingmeans comprising direct mechanical connections between the valve andsaid movable element, a three-way valve system for controlling flow ofgas to and from the chamber of the actuating mechanism, the three-wayvalve system including a shut-off valve located in said gas pressureconnections, and other actuating mechanism for operating the three-wayvalve system including a pressure responsive device communicating withthe distributing header.

2. The air-gas mixing apparatus described in claim 1 and in which thegas passage connections lead from the gas supply header to the actuatingmechanism chamber.

3. The air-gas mixing apparatus described in claim 2, and in which thechamber is also connected with the distributing header through thethree-way valve system for the exhaust of the gas pressure from thechamber into the distributing header.

4. The air-gas mixing apparatus described in claim 1, and in which theconnecting means through which gas flows from the supply chamber to thedistributing chamber includes a plurality of parallel connections eachof which includes its own mixer and its own valve for controlling theflow of gas through the aspirator, and each of which includes its ownactuating mechanism for the valve and three-way valve system, thepressure responsive devices of the different three-way valve systemsbeing constructed to operate at difierent pressures from one another andeach of the mixers including an air inlet passage which is relativelyshort to reduce flow resistance, and a light-weight, swing check valvein the air inlet passage operated entirely by the suction of theaspirator.

5. The air-gas mixing apparatus described in claim 1, and in which theactuating mechanism for the threeway valve system includes a conduitconnected with one of the headers for supplying gas pressure to saidactuating mechanism, and the pressure-responsive device includes a pilotvalve for controlling the flow of gas through said conduit to theactuating mechanism of the three-way valve system.

6. The air-gas mixing apparatus described in claim 5, and in which thepressure responsive device includes an energy-storing element operatedby the pressureresponsive device, a holder resisting movement of thepressure-responsive device, and connections through which said deviceoperates the pilot valve with a snap action when the stored energyovercomes the resistance of said holder.

7. The air-gas mixing apparatus described in claim 1, and in which theapparatus is a self-contained unit enclosed within a housing having bedmembers on which the housing and its contents are supported and movableas a unit, the gas supply header being enclosed within the housing andextending through a wall of the housing and having means for connectingwith a source of gas, the gas distributing header being also enclosedwithin the housing and having at least one end extending through a wallof the housing with means outside the housing for connecting with adistributing line, the con nections between the header being enclosedwithin the housing and including a plurality of parallel mixersconnected with a common air supply passage, and a single inlet through awall of the housing for flow of air from the ambient atmosphere to thecommon air supply passage.

References Cited in the file of this patent UNITED STATES PATENTS718,049 Dally Jan. 6, 1903 1,074,266 Jones Sept. 30, 1913 1,287,139Thompson Dec. 10, 1918 1,803,240 Fenzel Apr. 28, 1931 2,077,493 Rossi eta1. Apr. 20, 1937 2,366,322 Foster Jan. 2, 1945 2,570,373 Peacock Oct.9, 1951

1. AIR-GAS MIXING APPARATUS INCLUDING IN COMBINATION OF GAS SUPPLYHEADER FOR HIGH PRESSURE GAS, A DISTRIBUTING HEADER FOR AN AIR-GASMIXTURE AT LOWER PRESSURE, CONNECTING MEANS THROUGH WHICH GAS FLOWS FROMTHE SUPPLY HEADER TO THE DISTRIBUTING HEADER, SAID CONNECTING MEANSINCLUDING A PRESSURE REGULATOR AND A MIXER, AN ASPIRATOR IN THE MIXEROPERATED BY FLOW OF GAS THROUGH THE MIXER TOWARD THE DISTRIBUTINGHEADER, AN AIR INLET COMMUNICATING WITH THE ASPIRATOR AND THROUGH WHICHAIR IS DRAWN BY THE ASPIRATOR, A VALVE FOR CONTROLLING THE FLOW OF THEGAS THROUGH THE ASPIRATOR, ACTUATING MECHANISM FOR THE VALVE OPERATED BYGAS PRESSURE, GAS